MONTPELIER — Tapping maples in January is proving to be a tricky business this year because of extra cold temperatures.

Trees can withstand the winter cold but tapping into them during extreme weather risks cracking the bark and creating “a bigger wound,” said Kyle Branon of Branon Family Maple Orchards in Fairfield.

Temperatures in the state have plummeted to well below zero with wind chills of at least 29 below this month. But even a day like Wednesday, with readings in the upper teens, can be challenging, Branon said.

More than usual, maple producers should be careful not to create large splits above and below the tap that delay healing, said Tim Perkins, director of the University of Vermont Proctor Maple Research Center. Besides damaging the growth layer of the tree, the cracks also can reduce sap yield by creating leaks, he said.

In addition, cold temperatures present the risk of “sun scald,” which Perkins described as “sunburn on a tree.” The quick succession from bright sunlight to low temperatures kills a section of the bark. Young maples are especially vulnerable and mature more slowly if scalded, Perkins said.

The winter season so far has also included thaws. The National Weather Service recorded January temperatures at an average 18.1 degrees, lower than the usual 18.7 degrees, at Burlington International Airport.

“You’d think it’s been a normal January but we’ve really had some periods that were really cold,” meteorologist Andrew Loconto said. “Averages don’t tell the whole story.”

Variations, including a 10-day thaw with temperatures peaking at 52 degrees, counter the lows, which reached 15 degrees below zero three days so far this month. Brian Montgomery, a weather service meteorologist based in Albany who tracks a section of southern Vermont, saw similar temperatures at the Bennington airport.

“The last couple of winters have been milder,” Montgomery said. “This winter has set the reality back to what winters can be like in the Northeast.”

Despite the swings, weather watchers see no sign the rest of the winter will be unusual for New England, said David Unger, a weather service meteorologist at the agency’s Climate Prediction Center.

Ruth Goodrich of Goodrich’s Maple Farm in Cabot said the maple industry likes to see several thaws during the winter because that puts moisture into the ground.

But a sudden warm-up could hurt the trees more than cold snaps. Paul Palmer of Palmer Lane Maple in Jericho said that two years ago, unusually warm temperatures in March cut his maple production in half.

With the cold temperatures now and his smaller operation, Palmer said he will wait for warmer weather before tapping his trees. He said if he had to tap now, he’d worry about splitting them.

But Perkins said producers with more than 10,000 taps need to get started because it’s a time-consuming process.

Wednesday, Branon trekked into the woods to tap. It takes a full month for him to set all the taps. When asked how the maple season will go or how the cold snaps might affect his sugar maples, he said it was too early to predict.

“(As) the old sugar maker’s saying goes, I’ll tell you after we put the buckets away,’” he said.